A book about the election by Brian Cathcart was titled Were You Still Up for Portillo? In the Royal Festival Hall in London, the scene of the Labour party celebrations that evening, the result elicited a massive cheer, as Portillo was widely loathed among Labour supporters.[citation needed] Twigg was forced to give up his role as general secretary of the Fabian Society following this unexpected victory in what had been regarded as a safe Conservative seat. It was also unusual to have an openly gay British MP at that time.

In the 2005 election, Twigg lost his seat to the Conservative Party candidate, David Burrowes, by a margin of 1,747 votes (a swing of 8.7%).[9] During his concession speech, Twigg claimed that he would not be the last Labour MP for Enfield Southgate. He was proved correct in 2017, with the election of Bambos Charalambous, the Labour candidate, on 8 June.

On 12 December 2005, Twigg was arrested in central London for being drunk and incapable in a public place and taken to Marylebone police station. He paid a £50 fixed penalty notice. Twigg commented "I had had a lot to drink and I think it [the police action] was sensible. I have no complaints whatsoever. I take full responsibility for my actions."[10]

In October 2010 he unsuccessfully contested the election for the Shadow Cabinet, coming in 36th out of the 49 candidates and winning 55 votes.[13] He was subsequently appointed to the Labour front bench as a shadow minister in the Foreign Affairs team.[14]